Ovalona capensis (Rühe, 1921)

Sinev, Artem Y., 2015, Revision of the pulchella - group of Alona s. lato leads to its translocation to Ovalona Van Damme et Dumont, 2008 (Branchiopoda: Anomopoda: Chydoridae), Zootaxa 4044 (4), pp. 451-492: 474-476

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Ovalona capensis (Rühe, 1921)

comb. nov.

XII. Ovalona capensis (Rühe, 1921)  comb. nov.

( Figs. 8 A –DView FIGURE 8. A – D)

Rühe, 1921: 19–20, Fig. 5 a –bView FIGURE 5. A – H ( Alona  ); Smirnov, 1971: 341–342, Fig. 387 ( Alona  ); Van Damme, Bekker, Kotov, 2013: 442– 447, Fig. 1 –3View FIGURE 1View FIGURE 2View FIGURE 3, 4View FIGURE 4 b –c ( Alona  ).

Type locality. Simonstown, Western Cape, South Africa (established by Van Damme et al. (2013) for the lectotype).

Type material. Lectotype and two paralectotypes on same slide, Museum fur Naturkunde Berlin, (accession number 17 469).

Diagnosis. Diagnosis based on published descriptions. Parthenogenetic female. General. Length of adult up to 0.63 mm. Body low oval, height/length ratio about 0.55, maximum height at the middle. Postero-dorsal angle with about 50 setulae not organized into groups. Unlike in all other species of the genus, rostrum elongated, with large posterior bulge.

Head. Posterior part of headshield broadly rounded, with notches. Three major head pores without connection between them, PP less than 0.3 IP. Lateral head pores minute.

Labrum of moderate size, labral keel broad, with convex anterior margin and a rounded apex, posterior margin of keel with two clusters of setulae.

Second abdominal segment without dense setulae. Postabdomen moderately wide, with almost parallel margins in postanal portion, length about 2.5 heights. Distal margin straight; dorso-distal angle prominent, acute with rounded tip. Dorsal margin with distal part about 1.5 times longer than preanal one; anal and postanal parts of similar length. Postanal portion of distal margin almost straight; anal portion weakly concave. Preanal angle welldefined, postanal angle weakly defined. 7–8 short marginal denticles, decreasing in size basally and 3–5 groups of marginal setulae on anal margin. Eleven-twelve moderately wide lateral fascicles of setulae; in postanal portion, longest setule in each fascicle 2 times longer than marginal denticles. Postabdominal claw as long as preanal portion of postabdomen. Basal spine about 0.2 length of claw.

Antennule with antennular seta of 0.2 length of antennule, arising at 2 / 5 distance from the base. Aesthetascs of different length, two longest of them of about 1 / 3 length of antennule.

Antenna with seta arising from basal segment of endopodite reaching the end of endopodite. Spine on basal segment as long as middle segment. Spines on apical segments slightly longer than apical segments.

Limb I with accessory seta about 1 / 3 length of ODL seta. Limb III with exopodite seta 3 being longest; setae 4 about 2 / 5 length of seta 3; other setae shorter. Limb IV with epipodite without projection. Exopodite seta 3 longest; setae 1–2 about 2 / 3 length of seta 3; setae 4–5 about 1 / 2 length of seta 3; seta 6 shorter about 1 / 3 length of seta 3. Two basalmost flaming-torch setae (3–4) with reduced distal portion. Limb V with epipodite without projection. Exopodite seta 4 three times shorter than seta 1.

Ephippial female and male unknown.

Full redescription. See Van Damme et al. (2013).

Differential diagnosis. O. capensis  can be easily separated from all other species of the genus by presence of posterior bulge on the rostrum, and by unique morphology of postabdomen.

Distribution. Cape peninsula of South Africa.